Re: [dpdk-dev] [PATCH v2 0/2] mlx5/net: hint PMD not to inline packet

[Raslan Darawsheh <rasland@mellanox.com>]

Hi,

> -----Original Message-----
> From: Viacheslav Ovsiienko <viacheslavo@mellanox.com>
> Sent: Wednesday, January 29, 2020 2:21 PM
> To: dev@dpdk.org
> Cc: Matan Azrad <matan@mellanox.com>; Raslan Darawsheh
> <rasland@mellanox.com>; Ori Kam <orika@mellanox.com>; Shahaf Shuler
> <shahafs@mellanox.com>; thomas@mellanox.net;
> olivier.matz@6wind.com; ferruh.yigit@intel.com
> Subject: [PATCH v2 0/2] mlx5/net: hint PMD not to inline packet
> 
> Some PMDs inline the mbuf data buffer directly to device transmit
> descriptor.
> This is in order to save the overhead of the PCI headers imposed when the
> device DMA reads the data by buffer pointer. For some devices it is essential
> in order to provide the full bandwidth.
> 
> However, there are cases where such inlining is in-efficient. For example,
> when
> the data buffer resides on other device memory (like GPU or storage
> device).
> Attempt to inline such buffer will result in high PCI overhead for reading
> and copying the data from the remote device to the host memory.
> 
> To support a mixed traffic pattern (some buffers from local host memory,
> some
> buffers from other devices) with high bandwidth, a hint flag is introduced in
> the mbuf.
> 
> Application will hint the PMD whether or not it should try to inline the
> given mbuf data buffer. PMD should do the best effort to act upon this
> request.
> 
> The hint flag RTE_NET_MLX5_DYNFLAG_NO_INLINE_NAME is supposed to
> be dynamic,
> registered by application with rte_mbuf_dynflag_register(). This flag is
> purely vendor specific and declared in PMD specific header rte_pmd_mlx5.h,
> which is intended to be used by specific application.
> 
> To query the supported specific flags in runtime the private routine is
> introduced:
> 
> int rte_pmd_mlx5_get_dyn_flag_names(
>         uint16_t port,
> 	char *names[],
>         uint16_t n)
> 
> It returns the array of currently (over present hardware and configuration)
> supported specific flags.
> 
> The "not inline hint" feature operating flow is the following one:
> - application start
> - probe the devices, ports are created
> - query the port capabilities
> - if port supporting the feature is found
>   - register dynamic flag RTE_NET_MLX5_DYNFLAG_NO_INLINE_NAME
> - application starts the ports
> - on dev_start() PMD checks whether the feature flag is registered and
>   enables the feature support in datapath
> - application might set this flag in ol_flags field of mbuf in the packets
>   being sent and PMD will handle ones appropriately.
> 
> Signed-off-by: Shahaf Shuler <shahafs@mellanox.com>
> Signed-off-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>
> 
> ---
> RFC:
> https://eur03.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatch
> es.dpdk.org%2Fpatch%2F61348%2F&amp;data=02%7C01%7Crasland%40mell
> anox.com%7C7b9dad01f6f24fc054df08d7a4b5c1aa%7Ca652971c7d2e4d9ba6a
> 4d149256f461b%7C0%7C0%7C637158972862376366&amp;sdata=GVQd0sNOS
> 8Bbi3z33j2USdZpx%2FPE8IzwcfTg4QBj%2BwI%3D&amp;reserved=0
> 
> This patchset combines the parts of the following:
> 
> v1/testpmd:
> https://eur03.safelinks.protection.outlook.com/?url=http%3A%2F%2Fpatch
> es.dpdk.org%2Fcover%2F64541%2F&amp;data=02%7C01%7Crasland%40mell
> anox.com%7C7b9dad01f6f24fc054df08d7a4b5c1aa%7Ca652971c7d2e4d9ba6a
> 4d149256f461b%7C0%7C0%7C637158972862376366&amp;sdata=wpMH45Orli
> mz1y4Bd7Emb%2F%2Fz4hsu%2BLUMN8sortguMUE%3D&amp;reserved=0
> v1/mlx5:
> https://eur03.safelinks.protection.outlook.com/?url=http%3A%2F%2Fpatch
> es.dpdk.org%2Fpatch%2F64622%2F&amp;data=02%7C01%7Crasland%40mell
> anox.com%7C7b9dad01f6f24fc054df08d7a4b5c1aa%7Ca652971c7d2e4d9ba6a
> 4d149256f461b%7C0%7C0%7C637158972862376366&amp;sdata=RAA3Qw104
> dV6rujRoxXIOm0gcAI0DY5DyAdMAwryeb8%3D&amp;reserved=0
> 
> ---
> Ori Kam (1):
>   net/mlx5: add fine grain dynamic flag support
> 
> Viacheslav Ovsiienko (1):
>   net/mlx5: update Tx datapath to support no inline hint
> 
>  drivers/net/mlx5/mlx5.c                   |  20 ++++++
>  drivers/net/mlx5/mlx5_rxtx.c              | 106 +++++++++++++++++++++++++--
> ---
>  drivers/net/mlx5/mlx5_rxtx.h              |   3 +
>  drivers/net/mlx5/mlx5_trigger.c           |   8 +++
>  drivers/net/mlx5/rte_pmd_mlx5.h           |  35 ++++++++++
>  drivers/net/mlx5/rte_pmd_mlx5_version.map |   7 ++
>  6 files changed, 163 insertions(+), 16 deletions(-)
>  create mode 100644 drivers/net/mlx5/rte_pmd_mlx5.h
> 
> --
> 1.8.3.1

Series applied to next-net-mlx,

Kindest regards,
Raslan Darawsheh